As part of an examination of the trade deadline and team behaviors, Baseball America reviewed every July trade from 2003-12 that involved a prospect. (Trades from 2013-16 were not considered because many prospects involved are still climbing the minors.)

The finding? Only 69 of 366 prospects—or 18.9 percent—traded in deadline deals those 10 seasons went on to have productive MLB careers.

*MLB career defined here as two or more seasons on a major-league roster AND a positive career WAR.

There are a few reasons for such a low success rate. Prospects are inherently volatile, and the majority are bound to bust. But perhaps most importantly, the very best prospects—the ones expected to become true franchise cornerstones—are rarely traded in deadline deals.

“You stay out of a top 10 and you tend to stay out of big leaguers,” one pro scouting director said of making deadline deals.

Teams have long been reluctant to trade away their top prospects in all but the biggest deadline deals. But nowadays that reluctance has been amplified.

"It's nearly impossible (to get a top 20 prospect in a deal now)," the director said.

Still, scouts and front office officials devote thousands of hours to scouting the minor leagues every year in an effort to find prospects that are suitable compensation for a veteran at the trade deadline.

The harsh truth, history tells us, is those efforts most often end up being for naught.

NOTE: If you want to view the complete data set for these results, you can do so by clicking here.